Abstract

For a number of years, the extensive ecosystems of southern Africa have been a testing ground for ideas and techniques useful for studying and managing large-scale complex systems everywhere, and in particular for tackling issues of global change. The first contribution has been through making consistent, long-term, large-scale observations on climate, vegetation and animal dynamics and disturbances. These have been crucial in developing and testing hypotheses regarding how the earth system works at large space and timescales. The observational techniques have evolved dramatically over time: from notes kept by individuals, to systematic measurement programmes by organisations, to continuous and sophisticated measurements made by automated systems such as satellites and flux towers. The second contribution has been experimental, developing the notion that ecosystems can be the subject of deliberate experimental manipulation. Sometimes this has taken the form of large-scale treatments, such as fire trials or herbivore exclusion plots. More frequently, it has made use of the 'experiment' of the protected area in contrast to its surrounds, or has exploited the information in natural or human-induced gradients. Ecosystem experimentation has required rethinking the fundamentals of experimental design: What is the experimental unit? What is the meaning of a control? What constitutes replication? The third contribution has been theoretical. How does the functioning of warm, dry, species-rich ecosystems differ from the cool, moist, species-poor ecosystem examples that dominate the literature? What are the roles of disturbance and competition is maintaining ecosystem diversity, and top-down versus bottom-up control in maintaining ecosystem structure? The fourth contribution concerns the management of large-scale complex systems in the face of limited knowledge. How can the gap between science and policy be narrowed? What advantages and challenges does participatory co-management offer? How do you implement adaptive management?